Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 051742 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1242 PM EST Mon Dec 5 2016 .SYNOPSIS... Upper level shortwave trough which brought light rain to the area Sunday is moving east and off the coast. Brief clearing today in the wake of this system will be followed by more rain tonight and Tuesday as an area of Low pressure moves northeast from the Gulf of Mexico. After another break in the activity on Wednesday, a strong cold front will cross the region on Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 1041 AM EST Monday... High pressure over the Ohio Valley will build east this afternoon and reach southern New England tonight. This morning shortwave trough will push east further out into the Atlantic ocean. Made some some minor changes in temperatures and cloud cover for this morning into this afternoon. Adjusted temperatures with surface obs and tweak late morning into this afternoon with lamp guidance. High temperatures will depend on amount of sunshine before next system. Highs this afternoon will range from the lower 40s in the northwest mountains to the upper 50s in the piedmont. As of 530 AM EST Monday... Primary focus for wetting rain this morning will be the Tidewater of VA/NC. Rain has ended...at least for the next 12-18 hours...for the piedmont and mountains. Rain should also end for the Tidewater by afternoon with partial clearing all areas today before clouds reconvene and rain returns tonight and Tuesday. Lull in precip today is from mid level drying in wake of passage of an upper level short wave trough. Pooling of low level moisture will occur along a stationary front which extends from the Carolina Coast into the northern Gulf of Mexico, this moisture poised to move back into the forecast area tonight as low pressure over the western Gulf of Mexico strengthens and moves northeast along the stationary front. Regional radars indicate widespread rain is already occuring over southeastern TX and into LA. It is this area of precipitation that will move northeast today, reaching North Carolina before midnight...then spreading into the Virginias after midnight. Temperatures today will depend on amount of clearing that takes place. In spite of drying in the mid levels of the atmosphere, models indicate lingering moisture in both the low levels and upper levels. The low level moisture is expected to get mixed out be the brief surge of northwest downslope wind flow today, but its questionable as to whether the upper level moisture, cirrus level, will thin enough to permit more than a dim glint of sun. Per this thinking, went a few degrees below MOS guidance entertaining highs in the 40s mountains and lower to mid 50s for areas east of the Blue Ridge. Bigger temperature question will come into play tonight with models taking most areas back down into the 30s. A lot will depend on how much heating we get today and whether clouds will trap any of that heat permitting slightly warmer readings tonight. Since some of the models are entertaining the idea of some light wintry precip for the VA/WV highlands, a 1 or 2 degree temperature flucuation could make the difference between a cold rain versus some light sleet/freezing rain for the Shenandoah valley and the VA/WV Highlands. That said, even if those areas do test 32, any sleet or ice accretion should be minimal, only adhering to elevated surfaces as opposed to the ground (ground temps still too warm to permit travel issues). && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... As of 430 AM EST Monday... Model solutions have been very consistent in handling the upcoming system for Tuesday. Expect a strong,cold wedge east of the Appalachians to remain in place as low pressure moves out of the Mississippi delta with strong isentropic lift and upper dynamic support from the remnant of a closed low ejecting out of Mexico. This will bring widespread precipitation to the region through the first part of Tuesday before starting to taper off during the afternoon. The cold wedge will allow for some wintry mixed precipitation mainly from Greenbrier WV and the Alleghany Highlands southward to the higher elevations of the Blue Ridge, though no significant accumulations of snow or sleet is expected but a light glaze of ice is possible at the highest elevations. High pressure will then bring precipitation to an end early Wednesday before a strong cold front moves through early Thursday. There is not a lot of moisture with the front so will confine any higher POPs to upslope areas west of the Blue Ridge, and a plume ahead of the front may generate some precipitation east of the Ridge as well. Colder air will then rapidly move in behind the front and change precipitation over to snow showers for upslope areas before tapering off. Any accumulations will be quite light. Winds will also become blustery as temperatures plummet, creating wind chills down to the single digits west of the Ridge with teens to the east. && .LONG TERM /FRIDAY THROUGH SUNDAY/... As of 430 PM EST Monday... Will turn windy and much colder Friday although appears speeds still below advisory levels with wind chills zero/single digits. Arctic high finally builds overhead by Saturday allowing for the coldest temps by early morning before the trough starts to lift out allowing some moderation Saturday afternoon into Sunday in response to return warm advection. Next weak system coming out of the Rockies may tap enough return moisture to bring a band of light mix to the far west by late Sunday. However without much southern connection appears precip limited given residual dry air and could be just clouds and spotty rain if things slow up more so only low pops for now Sunday. Expect highs only in the 20s mountains to 30s east under a blustery northwest wind Friday. Lows Friday night mostly teens unless high clouds invade more late, then warming to highs in the 30s and 40s for the weekend. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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As of 1242 AM EST Monday... High pressure to our north will provide brief drying this afternoon before rain returns tonight and Tuesday. Lower clouds associated with this mornings shortwave have eroded and moved east into the Atlantic ocean. Moisture will quickly return tonight. Low pressure over the western Gulf of Mexico is progged to move northeast, rain overspreading the region from southwest to northeast during the overnight, reaching western NC after midnight, then into the Virginias Tuesday morning...and associated with widespread IFR VSBY and CIGS. Northwest winds northwest 5-10kts this afternoon, will become light northeast after 21Z/4PM, before increasing again during the overnight from the southeast as the storm system approaches from the southwest. Rain will continue Tuesday with widespread IFR/LIFR conditions. A brief period of IP or freezing rain may be possible across the northern mountains, mainly Greenbrier and Bath counties. However, temperatures warm up quickly Tuesday morning. Not expected any problems at taf sites. IFR/LIFR conditions Medium confidence in ceilings, visibilities and winds during the taf period. Extended aviation discussion... Rain associated with IFR/LIFR conditions Tuesday afternoon into Tuesday night will be followed by partial clearing Wednesday. This break in the weather will be followed by a cold front Thursday, this front bringing a surge of cold air. Look for a return of sub- VFR conditions, this time associated with snow showers across the mountains Thursday night into early Friday. Friday, expect a gusty day across the region with lingering upslope cloud and snow showers between KBLF-KLWB. East of the Blue Ridge, VFR is expected.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...KK/PM SHORT TERM...MBS LONG TERM...JH/MBS AVIATION...KK/PM

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